Extreme pressure soap and complex thickened greases



United States Patent 3,396,108 EXTREME PRESSURE SOAP AND COMPLEX THICKENED GREASES Gerard P. Caruso, New Orleans, La., assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware No Drawing. Filed Dec. 22, 1964, Ser. No. 420,425

7 Claims. (Cl. 252-18) This invention relates to non-clay thickened grease lubricants having improved extreme-pressure properties. More particularly, the invention relates to certain soapand complex-thickened greases which are improved with [regard to their ability to lubricate properly under extreme pressure (EP) conditions.

Prior to about 1940, nearly all grease requirements were met with uninhibited mineral oil thickened with calcium, sodium, or aluminum soaps. However, in the early 1940s the discovery of lithium soap thickened greases led to the development of water-resistant greases having high melting points and superior low-temperature properties. Later, in the 1950s, the discovery of lithium hydroxystearatethickened greases paved the way for multi-purpose greases having excellent shear stability coupled with water resistance and good highand low-temperature properties. In the late 1950's the need by industry and the armed forces for improved performance at temperatures ranging from -100 to +600 F. led to the development of many new types of oils, thickeners and additives.

While new thickeners, particularly waterproofed clays, have opened new vistas of grease performance, soapthickened and complex-thickened greases still represent by far the major part of grease production and use in the world.

One of the major problems in the formulation of greases, particularly non-clay-thickened greases, is that of extreme-pressure (EP) properties, that is, the formulation of greases which have high film strength under high pressures. Literally thousands of materials of highly varying degrees of effectiveness, have been proposed to improve the EP properties of conventional greases. Among the many types of EP additives are sulfur, selenium and tellurium compounds, metal chlorides and sulfides and the like, In particular, certain metal sulfides, which are themselves good solid lubricants having EP properties, have been suggested for incorporation into grease. Among the metal sulfides which have been tried are antimony sulfide, molybdenum sulfide and zinc sulfide. However, such metal sulfides have not generally been found to be satisfactory EP agents in grease without the use of other additives to reduce the abrasiveness of such materials. For example, it is disclosed in US. 2,285,739 to use lead naphthenate in conjunction with zinc sulfide to reduce the abrasiveness of the metal sulfide. However, despite the extensive work on the use of metal sulfides in grease, the degree of EP efiectiveness heretofore attainable in view of the cost of such lubricants, has not been sufiicient to bring about their widespread application. Though, recently, waterproofed clay-thickened EP greases containing amorphous metal sulfides (antimony or molybdenum) have become available and are gaining increasingly wide acceptance, soapor complex-thickened greases having comparable EP properties have been hitherto unobtainable.

However, applicant has now discovered that soap or complex greases having excellent EP properties can be made economically by incorporation therein of amorphous antimony trisulfide. More particularly applicants invention is a naphthenate-free grease composition consisting essentially of (1) a lubricating base oil containing minor amounts each of (2) an oil-soluble sulfonate corresponding to the formula discolor) 3,396,108 Patented Aug. 6, 1968 wherein A is selected from the group consisting of alkali metal, alkaline earth metal, ammonium and omega-amino alkyl ammonium, n equals the valence of A and R is a monoyalent hydrocarbyl radical selected fromthe group consisting of alkyl, aryl, alkaryl or aralkyl groups containing at least 6 carbon atoms, and (3) a metal sulfide primary EP agent, the lubricating oil being th ckened to grease consistency by means of a soap-base thickening agent.

By the term soap-base thickening agent, as used herein, is meant metal soaps of fatty acids which are capable of providing a stable gel structure to lubricating base oils. The term is intended to include conventional metal soaps, complex soaps, mixed base soap greases, and the like, and includes the following particular types of soap thickeners:

Metal base:

Aluminum base Barium base Calcium base Lithium base Sodium base Lead soap base Strontium base Mixed bases:

Sodium-calcium base Sodium-barium base Calcium-aluminum base Sodium-aluminum base Magnesium-aluminum base Lithium-aluminum base Metal complex:

Hydrated calcium soap Hydrated aluminum soap Hydrated barium soap Hydrated lithium soap Hydrated sodium soap Hydrated strontium soap Complex aluminum soap Complex barium soap Aluminum-barium complex Aluminum-sodium complex Complex calcium soap Calcium soap-calcium acetate complex Calcium soap-calcium chloride complex Calcium soap-strontium hydrate complex Calcium-barium soap complex Lithium soap-lithium acetate Magnesium soap complex Lead soap complex Sodium soap-sodium acetate complex Sodium soap-sodium acrylate complex Sodium-barium complex Strontium-calcium acetate complex Though the lubricating base oil component of the invention can be either a natural or synthetic oil, as a practical matter, the base oil will usually be a natural oil, e.g. a petroleum-derived mineral oil. Many synthetic oils such as silicone oils and various esters can be thickened effectively with soap thickeners; however, the thermal stability of soaps is usually considerably lower than the synthetic oils. Therefore there is usually no point in using expensive synthetic oils with soap greases. Exceptions to this, however, are some of the complex greases which possess considerably higher thermal stability than the conventional soap-base greases.

The sulfonates which are useful in accordance with the invention are the salts of alkali metals or alkaline earth metals and oil-soluble monosulfonic acids. These are fre quently of petroleum origin. Examples of typical suitable sulfonates are given in the following table.

TABLE L-ANALYSES OF TYPICAL SULFONATES Barium Sodium Ammonium Ethylene Sodium Calcium Barium Strontium Dinonyl Dinonyl Dinonyl D amlne Petroleum Petroleum Petroleum Petroleum Naphthalene Naphthalene Naphthalene Dinonyl Sulionate Sulfonate Sultanate Sulfonate Sulionate Sulfonate Sulionate Naphthalene Sulfonate Sulfonate, percent wt 62 41 40 31 50 50 50 50 Mineral Oil, percent wt 33 58 59 68 46 46 46 46 Water, percent wt 0. 5 1 0. 5 1 0. 2 I 0.2 1 0. 2 I 0.2 Inorganic Salt, percent wt- None 1 1. 5 1 None None None None Molecular Weight 400/470 ca. 890 980/1, 010 1,055 482 477 980 1 Maximum. Q The metals which can be used in the sulfonates are the Example II alkali metals (Periodic Group IA) sodium and potassium and the alkaline earth metals (Periodic Group HA), calcium, strontium and barium.

Within the context of the foregoing chemical structural formula (Remit a) when A is omega-amino alkyl ammonium or alkyl ammonium, the alkyl portion thereof contains from 2 to 6 carbon atoms. A process for the preparation of sulfonates of this type is disclosed in U.S. Patent 2,764,548 issued Sept. 25, 1956. The ammonium sulfonic acid salts are prepared by reaction of the sulfonic acid with aqueous solutions of appropriate aliphatic or aryl primary, secondary or tertiary amines, e.g. dimethylamine, ethylenediamine, mono-, diand triethyleneamine'. The metal sulfides which are used as the primary EP agent in the grease composition of the invention include molybdenum disulfide, an

amorphous antimony sulfide and mixtures thereof. The' amorphous antimony sulfide is specified as contrasted to the crystalline antimony sulfides. The latter, normally obtained by the mining of certain minerals such as stibnite,

actually causes abrasion of metallic parts. This may be due either to the extreme hardness of crystals or may be due to naturaLOccurring impurities such as silicates or silica present in the mineral. The amorphous antimony sulfides (e.g., antimony trisulfide, antimony tetrasulfide, or antimony pentasulfide and mixtures thereof) vary in color from yellow to gray but usually are some variety of red, dependent upon the precise means of preparation and more particularly upon the particle size of the amorphous sulfide. They are preferably obtained by precipitation of the antimony sulfide from an aqueous solution of a watersoluble antimony salt, such as antimony chloride, by treatment with a sulfide such as sodium sulfide or hydrogen sulfide.

The term primary EP agent is applied to the metal sulfides within the context of the invention; since, as will be shown by the following examples, the metal sulfides are substantially ineffective to improve the EP properties without the presence of the above-described sulfonates.

Example I Sample Designation A B C D Aiiltrttimony Trisultlde, percent 0.75 1.0--.." 1.0 5.0. Consistency:

ASTM Penetration:

Unworked. 282 Worked 271 NLGI Grade No. 2 No. 2 No. 2. Timken EP Value, pounds. Fail 20. Fail 20. Fail Fail 30.

I ASTM penetration range, 265-295.

A further series of experiments was then run in which the greases to which the antimony trisulfide was added also contained a minor amount of an alkaline earth metal sulfonate, in this case calcium petroleum sulfonate. Some of these greases, all of which are commercially available lubricants, also contain minor amounts of naphthenic acids or metal naphthenates as indicated. The data show that the metal sulfides are quite effective to improve the EP properties of the soap base greases but (1) only in the presence of the metal sulfonates and (2) only so long as 'the grease is free of any naphthenic acids or naphthenates.

TABLE III.EP PROPERTIES OF SOAP BASE GREASES CONTAINING METAL SULFIDE AND SULFONATES Formulation E F G H I J K L Soap 9.1 8.8 8.8 8.6 9.1 9.0 8.6 8.5 Lubricating Base 011". 86. 5 85.3 85. 7 86. 0 85.9 85.8 88.8 87. 5 Calcium Sulfonate 2.8 2.8 2.8 2.9 2.9 2.9 1.0 3.0 Amorphous SbzSa 1. 0 1. 0 1. 0 1.9 l. 5 1. 5 1. 0 1. 0 N aphthenate 0. 1 0. 1 0. 6 0. 2 0. 6 Corrosion Inhibitor... 0.6 1. 4 0. 9 0. 6 0. 6 Other Additives 0. 6 0. 7 Timken EP Value,

pounds:

Pass 25 20 FaiL 2O 20 30 55 25 20 1 Soap oi LiOH-H2O and hydrogenated fatty acids. All formulations given on percent weight basis.

2 Ethylene diamine dinonyl naphthalene sulfonate.

It is interesting to note from the above data (Formulation H) that even increasing the amount of metal sulfide failed to overcome the adverse efiect of the presence of even a small amount of naphthenate.

The above data, Formulations K and L, indicate that the interaction of amorphous metal sulfides with sulfonates is not restricted to metal sulfonates but applies to organic salts of sulfonic acids as well. This is confirmed in the following example.

Example III TABLE IV.EP PROPERTIES OF SOAP BASE GRE TAININ G METAL SULFIDE AND N ON-METAL Formulation Soap, percent wt. Lubricating Base 0 Amorphous SbzSs- N on-metal Sulfonate The amounts of metal sulfide and metal sulfonates which are to be used in the soap EP greases of the invention can each be varied from about 0.5 to about 10.0%, 1 to 5% by weight of each being preferred. The ratio of sulfonates to metal sulfide does not appear to be critical.

Example IV The quite unexpected interaction of the sulfonates and the amorphous metal sulfides is perhaps most graphically illustrated in view of the facts (1) that the metal sulfide TABLE V.EP PROPERTIES OF METAL SULFIDE- CONTAINING OLAY-THICKENED GREASES Formulation N O Clay-thickened Grease. 96. 99. 5 Amorphous SbzSs 0. 5 0. 5 Calcium Petroleum Sulionates 3. 0 None Timken EP Value, pounds:

Pass 40 40 Fail 45 In the following table, a number of diiferent grease formulations within the scope of the invention are exemplified.

TABLE VI.SOAP BASE EP GREASES CONTAININGS%%% 2. The composition of claim 1 in which the mixture (3) consists of (a) calcium petroleum sulfonates and (b) amorphous antimony trisulfide.

3. The composition of claim 1 in which the mixture (3) consists of (a) sodium petroleum sulfonates and (b) amorphous antimony trisulfide.

4. The composition of claim 1 in which the mixture (3) consists of (a) omega-amino-C alkyl ammonium alkaryl sulfonate and (b) amorphous antimony trisulfide.

5. The composition of claim 1 in which the mixture (3) consists of (a) ammonium alkaryl sulfonate and (b) amorphous antimony trisulficle.

6. A soap base grease composition having improved extreme pressure properties consisting essentially of (l) a lubricating base oil thickened to grease consistency with (2) a thickening amount of the lithium soap of 12- hydroxy stearic acid and (3) a mixture containing 0.5- 10.0% by weight, basis total composition, each of (a) calcium petroleum sulfonates and (b) amorphous antimony trisulfide, the composition being further characterized as containing no naphthenate compounds.

7. A soap base grease composition having improved extreme pressure properties consisting essentially of (1) AL SULFIDES AND ALKALI- OR ALKALINE EARTH-METAL ONATES Thickening Agent Metal Sulfide Sulionate Lubricating Base Oil,

percent wt. Percent Type Percent Type Percent Ty e weight weight weight 500 SSU at 100 F. Neutral Oil:

32,0 10. 0 Alumdinum soap of dimerized fatty 5.0 Amorphous SbzSz.-- 3. 0 Sodium petroleum,

aci s. 10. 0 .do 1.0 0.5 Calcium petroleum. 12. 1 Calcium 12hydroxystearate 0. 05 5. 0 Do. 11. 0 d0 1.0 3.0 Barium petroleum.

8. 8 Barpum soap of hydrogenated caster 1 0 3. 0 Do.

01 10. 6 Bariuim and calcium soap of fatty 1. 0 M082 4. 0 Potassium petroleum.

an s. v /30 mixture of 750 SSU at F.

red oil and HVI bright stock:

ll. 2 Hydrated calcium soap of palm oil- 1. 5 MoS2--.. 2. 7 Sodium petroleum.

12. 4 Calcium soap of lard oil 2. 0 M0S2.... 1. 4 Calcium petroleum.

6. 3 Callcium acetate-calcium soap com- 0. 05 Amorphous SbzSa- 3. 2 Do.

p ex. 1 Litthiunll soap of hydrogenated cas- 1.0 ...do 1.0 Barium petroleum.

or or Lithium and aluminum soap of 1. 0 .....do 4. 2 Strontium petroleum.

stearic acid. Sodium soap of 12-hydroxystear1c 1.0 -do 5. 0 Barium dinonyl acid. naphthalene. Complex lead-sodium fish oil soap- 2.0 .....do 2. 0 Sodium petroleum.

Sodium soap oi tallow fatty acids-.. 2. 0 ...do 2. 0 Do. Mixed magnesium and aluminum 5. 0 ..do 3. 0 Calcium petroleum.

12-hydroxy stearate. Lithium soap oi hydrogenated eas- 1 0 do 3. 0 Ethyl ammonium tor oil. 0111-18 alkyl. ..do 1. 0 -do 3.0 Ammonium dloctyl naphthalene.

I claim as my invention:

1. A soap base grease composition having improved extreme pressure properties consisting essentially of (1) a lubricating base oil thickened to grease consistency with (2) a thickening amount of metal-containing soap, and 3) a mixture containing 0.5-10.0% by weight, basis total composition, each of (a) an oil-soluble sulfonate corresponding to the formula a lubricating base oil thickened to grease consistency with (2) a thickening amount of the lithium soap of 12- hydroxy stearic acid and (3) a mixture containing 0.5- 10.0% by weight, basis total composition, each of (a) ethylenediamine dinonylnaphthalene sulfonate and (b) amorphous antimony trisulfide, the composition being further characterized as containing no naphthenate compounds.

References Cited UNITED STATES PATENTS 2,421,543 6/1947 Cook 252l8 2,511,250 6/1950 Fa-wcett 252--33.2 2,540,533 2/1951 Ko'lfenbach et al. 252--33.2 2,540,534 2/1951 Kolfenbach et a1. 252-332 2,764,548 9/1956 King et a1. 25233 2,846,392 8/1958 Morway et a1 252-39 3,015,623 1/1962 Loring et a1. 252-18 3,269,947 8/ 1966 Swenson 252-332.

(Other references on following page) 7 8 OTHER REFERENCES Advances in Petroleum Chemistry and Refining by Petroleum Refining Chemicals Kalichev ky Ct 211., IntelSC'wnCe P1111, New York, pp. et -a1., Elseiver Pub. 00., New York, 1956, p. 582.

Manufacture and Application of Lubricating Greases I by Boner, Reinhold Pub. Corp., New York, 1954, pp. 6 DANIEL WYMAN Emmmer- 760, 761, 781, 782. I. VAUGHN, Assistant Examiner. 

1. A SOAP BASE GREASE COMPOSITION HAVING IMPROVED EXTREME PRESSURE PROPERTIES CONSISTING ESSENTIALLY OF (1) A LUBRICATING BASE OIL THICKENED TO GREASE CONSISTENCY WITH (2) A THICKENING AMOUNT OF METAL-CONTAINING SOAP, AND (3) A MIXTURE CONTAINING 0.5-10.0% BY WEIGHT, BASIS TOTAL COMPOSITION, EACH OF (A) AN OIL-SOLUBLE SULFOANTE CORRESPONDING TO THE FORMULA 